R.K.
Traditionally the groom's parents pay for the rehearsal dinner. The groom pays for the brides bouquet, the brides parents pay for the rest of the flowers.
Start shopping for your dress as soon as possible. Try to find a dress to blend in with the bridal colors, but not match. It will be a lot easier to select the flowers for your corsage if they know the color of your dress.
Best advice... ask the bride and her parents what they want you to do. They may want you to be very involved and they may just want you to do only what is necessary.
Ask about the guest list.. how many people they want to invite and if it should include extended family. I remember when I got married his family asked about the guest list and my Mom said aunts, uncles, and cousins. When I met my MIL's aunt later I asked why she wasn't invited to the wedding and my MIL said she didn't think she was included. My family includes EVERYBODY, his family didn't realize I meant all of them. So ask specific questions.